Conventionally known is a horizontal articulated robot which configures part of an EFEM (Equipment Front End Module) and which transfers semiconductor wafers between a FOUP (or multiple FOUPs) and a semiconductor wafer processing apparatus (Patent reference 1, for example). The industrial robot disclosed in Patent reference 1 is provided with two hands on which semiconductor wafers are to be mounted, an arm, to which the two hands are rotatably joined to the front end thereof, and a main body portion, to which the base end of the arm is rotatably joined. The arm is configured by a first arm, of which the base end is rotatably joined to the main body portion, a second arm, of which the base end is rotatably joined to the front end of the first arm, and a third arm, of which the base end is rotatably joined to the front end of the second arm and to which the hands are rotatably joined to the front end thereof. An arm-elevating mechanism is housed inside the main body portion to raise and lower the first arm.
Also, known as a vertical articulated robot is one equipped with a base, a body fixed to the base, a first arm which is rotatably joined to the body, a second arm which is rotatably joined to the first arm, a wrist which is rotabaly joined to the second arm, and fingers which are rotatably joined to the wrist (see Patent reference 2, for example). In the vertical articulated robot disclosed in Patent reference 2, a level for adjusting the original position is attached to the first arm and the fingers.
Also, conventionally known is a horizontal articulated robot for transferring semiconductor wafers (see Patent reference 1, for example). A horizontal articulated robot disclosed in Patent reference 3 is equipped with a hand on which semiconductor wafers are to be mounted, an arm to which the hand is rotatably joined to the front end thereof, and a base to which the base end of the arm is rotatably joined. The arm is configured by a first arm portion, of which the base end is rotatably joined to the base, and a second arm, of which the base end is rotatably joined to the front end of the first arm portion and to which the hand is rotatably joined to the front end thereof.
In the horizontal articulated robot disclosed in Patent reference 3, a turning drive means is equipped to rotate the second arm portion with respect to the first arm portion. The turning drive means is provided with a motor which is arranged inside the first arm portion such that the axial direction of the output shaft coincides with the horizontal direction, a first bevel gear which is coupled with the output shaft of the motor, a second bevel gear which meshes with the first bevel gear, a third gear which is formed at the bottom end of a cylindrical protrusion secured to the base end of the second arm portion, and a second gear which meshes with the third gear and is formed integrally with the second bevel gear.